, 2003), suggesting that exon 5 inclusion results in decreased dendritic localization. Moreover, Tanc proteins interact with PSD-95, a protein involved in localizing NMDARs at the synapse ( Han et al., 2010). Thus, a decrease in dendritic GRIN1 or altered regulation of NMDARs TGF-beta inhibitor could underlie the decrease in the synaptic NMDAR response, impaired LTP, and learning

and memory deficits. While there have been sporadic reports of epilepsy associated with DM, this is not a characteristic overt feature of this disease (Meola and Sansone, 2007). However, DM patients show enhanced sensitivity to barbituates and benzodiazepines, which enhance the activity of the GABAA receptor (Harper, 2001). Moreover, the relevance of this hyperexcitability phenotype to DM1 is also supported by our observation that seizures were induced with a GABA antagonist in both Mbnl2 knockouts and the DMSXL transgenic model for DM1. Because the expression of a large CTG expansion in the DMSXL brain is sufficient to increase seizure susceptibility in mice, this study provides

the cautionary note that DM may possess some features of an excitability disorder. Finally, we also noted a difference in the latency time to the appearance of the seizure phenotype between males and females, which could reflect sex-specific differences in the alternative splicing of seizure-associated genes. Based on these and additional findings, we propose a modified MBNL combinatorial loss-of-function model for GABA activity DM. MBNL proteins function as alternative splicing factors during postnatal development, with MBNL2 the predominant factor in the brain, while MBNL1 serves a similar role in skeletal muscle (Figure 7E). Thus, we anticipate that major pathological changes in the DM brain are attributable

to toxic RNA expression, MBNL2 sequestration by Docetaxel purchase C(C)UGexp RNAs, and dysregulation of specific alternative splicing events required for normal adult CNS function. The Mbnl2 targeting vector was derived from CHORI clone bMQ-63F6. A 10 kb fragment containing Mbnl2 was subcloned into PL253 (protocols 1–4, http://web.ncifcrf.gov/research/brb/protocol.aspx). The targeting construct ( Figure S1B, Table S3 for PCR primers) was linearized with NotI and electroporated in 129 SvlmJ ES cells, followed by selection as described ( Kanadia et al., 2003). For constitutive Mbnl2 knockouts, Mbnl2+/con mice were mated to B6.C-Tg(CMV-cre)1Cgn/J mice (JAX). All animal procedures were approved by the University of Florida IACUC. Mouse tissue protein and RNA analyses ( Kanadia et al., 2006), immunohistochemistry and X-Gal staining ( Emamian et al., 2003), and rotarod analysis ( Daughters et al., 2009) were performed as described previously with some modifications (see Supplemental Experimental Procedures). Implant surgery, EEG/EMG monitoring, and EEG data acquisition were performed on 6-month-old mice (n = 8 for each genotype) as described (Fujiki et al., 2009).